Electric bell



(No Model.)

M. G. CRANE.

ELECTRIC BELL. No. 388,836A Patented Sept. 4, 1888.

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C E5 J- f 19' x ,I a a 5 lfm/e for N PEYERS. Pham-Langman, wunmgton. D C.

UNITED STATES PATENT OFFICE.

MOSES G. CRANE, OF NEVTON, MASSACHUSETTS.

ELECTRIC BELL.

SPECIFICATION forming part of Letters Patent No. 388,836, dated September 4, 1888.

Serial No. 5170.045. (No model.)

To all whom it 71mg/ concern:

Beit known that I, MosEs G. CRANE, of Newton, county of Middlesex, State of Massachusetts, have invented an Improvement in Electric Bells, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

The object ofmy invention is to produce an electric bell capable of being controlled by a current of moderate strength, such as conimonly employed in a normally-closed circuit or main line for a fire-alarm telegraph or similar apparatus, and which is operated to strike the blow upon the gong by a stronger current applied only while the bell-hammeris making its forward movement to strike the blow.

It is necessary in order to strike a sufficient blow on a large bell that the hammer should have a long and forcible stroke, which, if the hammer is actuated directly by the magnet, involves a considerable separation ofthe armature from the magnetpoles. Itis well known that the attractive force diminishes rapidly as the distance of the armature from the poles increases, and for this reason it has been impracticable to operate large-sized bells by the direct action of the currents commonly employed in normally-closed telegraphic circuits, and such large-sized bells have usually been operated by a mechanical motor and controlled only by the electric current.

In the present invention the bell-hannner is actuated by the strong current of a powerful battery which is normally in open circuit; but its operation in controlled by the weaker current in the normally-closed circuit, which is snllicient to hold the armature when near the poles of the magnet.

The invention is embodied in an apparatus comprising an electromagnet and its armature, a bellAhammer connected with and operated by the said armature, and an electric switch operated by the said bell-hammer at the end of its movements in each direction, combined with a main circuit and circuit-controller which govern the operation of the said bellhammer, and a local circuit and battery therein governed by the switch operated by the bell-hammer, said local circuit being closed at the end of the baekstroke and opened at the end of the forward stroke of the bell-hammer, so that its current actuatcs the said bell-hammer in its forward movement, by which the blow is struck, (or conversely.) A loekingdevice is also provided vfor arresting the bellhammer in its forward position independently ofthe attraction of its magnet, so that it will not fall back or be retracted on the opening of the local circuit at the end of the forward stroke. The said lock or catch retains the bcll-hammerand armaturein the forward position near the poles of the magnet, but admitting of a slight additional forward movement when the magnet is energized bythe action of the main or controlling circuit, such slight additional forward movemcntrcleasing the lock or catch,so that the bell-hammer can make its return movement when the magnet is demagnetizcd by the subsequent action of the main circuit, this construction insuring hat the bell-hammer will respond with a single blow to each complete change or closure and subsequent break of the main circuit.

Figure lis a front elevation of an electric bell embodying this invention, the circuits being shown in diagram; Fig. 2, an enlarged perspective view of the lock for the bell-hammers, and Fig. 3 a detail showing the construction of the magnet-poles and armature in elevation 011 a plane at right angles to that of Fig. l.

l'he instrument comprises a controlling and actuating electromagnet, a, and armature b, pivoted at b and provided with an arm, b2, the extremity of which constitutes the bellhammer b3, the said armature and bellhznn mer being perferably made in a single casting of malleable iron.

The poles c' ofthe magnet a have large ex tensions, which may be made integral with the core-piece in the casting or may be fastened upon the said core piece, said pole-pieces a having lugs a?, between which are pivoted lugs c, composed of brass or other non-magnetic material attached to the armature, which is thus pivoted directly upon the poles, although not affording a direct magnetiecontact con ncction between the poles when the armature IOO is retracted. This construction of the mag net and its armature is not herein clailned, as it forms the subject of another application for Letters Patent.

ln the forward movement of the armature produced by the attraction ot' the magnet (L it is arrested by a stop, d, so that the hammer If will not remain in contact with the gong (a portion of which is shown at e) after the blow is struck.

The hannner and armature may be retracted bygravity when the instrnmentis set in proper position; but the armature is shown as provided with a rctracting-spring,j', and it also has a spring-finger, g, which arrests the hammer at the end of the stroke by coming in contact with a stationary stop, y', as shown in dotted lilies, Fig. l, thus stopping the hammer without shock and tending to start it with an elastic impulse on its forward stroke.

The armature and the hammer just at the end of the stroke in cach direction engage and operate a switch, h, pivoted at h' and provided with canrsurfaees l1,2 h, which are engaged byan actuating projection, h", on the hammerarnl moving the end of the switch onto and off from a contact-plate, yi, and thus closing and opening a circuit terminating in said switch and contact-plate at the end ofthe backward and forward strokes of the hammer, respectively, and leaving said switch closed during substantially the whole forward stroke, and open during substantially the whole baek ward stroke, ofthe hammer.

rlhe operation of the bell is controlled by a main circuit, 2 l3 4 5, including a battery, B, and a circuitchangcr-such, for example, as the break-wheel C-the said main circuit, as shown in this instance, including the magnet a, and its current being sufficient to retain the armature b attracted when the said armature is close to the poles of the magnet, but not necessarily being sufficient to move up the ar mature from its retracted posit-ion with sufficient force to give the desired stroke on the bell. The bell-hammer would thus respond to a break in the main circuit by falling back, and when it is once released or permitted to fall back by the main circuitits forward stroke is produced independently of the action ofthe main circuit by means of the local circuit 6 7 8, connected with the terminals 3 .4 of the mag net a and including a battery, l, the said local circuit terminating in the switch h and its eontact-plate z', so that the moment the said switch is closed by the action of the pin h4 011 the cam hIl at the end of the backward stroke, permitted by the breaking of the main circuit, as just described, the current of the battery B passes through the magnet e and causes the armature and hammer to make the forward stroke, by which the bell is struck.

The battery B is normally in open circuit and may be sufficiently strong to cause the hammer to strike a powerful blow, andit will not be rapidly exhausted, as it works only during the forward stroke of the bell-hammer,

at the end of which the projection hl engages the cam l1," and opens the local circuit.

lf the break in the main circuit is only momentary, so that it closes again before the hammer finishes its forward stroke ,it will retain the armatureattracted, so that only one stroke will be given for such momentary break in the main circuit; but it will be seen that if the break in the main circuit should continue beyond the time occupied by the hammer in making its complete backward and forward movement-as, for example, by an accidental rupture of the main line-the said hammer might continue to operate under control only of the local circuit and switch, like an automatically-vibrating bell, which may not be desirable. In order to guard against this and to insure that the bell-hammer will make only one stroke for each break in the main circuit, it is provided with a lock, m, made movable in such manner as to permit the forward and backward strokes of the bellhannner at the proper times, but to arrest the bell-hammer after it has completed its forward stroke in case the magnet a is not energized by the ac tion of the main circuit at this time. The lock m is shown in this instance as movable on a pivot, m, and normally, when l'ree to move, is held against a stop, m2, by the action of a light spring, m, or weighty such as indicated in dot ted lines at mt.

The 11am mer-arm b'l is provided with a projection, a, that eo-operates with the lock m, andthe said lock is provided with a groove, m, which, when the said lock is held against its stop m2,is concentric with the pivot b ofthe armature, so that the projection n will pass freely through said groove in the back-stroke of the hammer. rlho lower end of the said groove is closed by a light spring, in, which yields to permit the projection a to pass as the hammer makes its backstroke, butcloses over the end of the groove lfimmediatcly after the projection a has passed through, so that when the hammer makes its forward stroke the projection a will engage the said spring a", and thus, instead of passing through the groove a, as it did on its downstroke, it will pass along the front of the lock m, turning the same on its pivot to the position shown in dotted lines, Fig. l.

lImmediately after the proj ection alias passed the front of the lock m and turned itaside on its pivot, as just described, the said lock will tend to return to its normal position against the stop im2 by the action of the spring m or weight m", but it will occupy little time in com ing to this position, and ifthe magnete be not energized when the hammer completes its forward stroke the latter will move back almost instantly by its rebound, and will thus strike on the upper end, mi, of the lock before the the latter is moved far enough to bring the groove mi in liuc with the said pin a, thus preventing the armature and hammer from moving back. The downward or backward pressure of the bell-hammer willprevcnt further IZO movement of the lock, which will thus re tain the armature close to the magnet-poles as long as the magnet remains demagnetized. 'Ihe end of the lock may be provided with a slight projection, ms, to insure greater certainty of engagement with the pin a in case the hammer begins to make a return movement immediately after its forward stroke. The hammer will remain thus locked in position, with the armature close to the poles of the magnet, until the main circuit is closed, when the armature will be again attracted, and the relieving of the pressure of the pin a upon the upper end of the lock m and slight forward movement of the armature will permit the latter to be turned by its weight or spring to the normal position with the groove a5 in the path of the projection a, so that it can make another stroke, as before described, upon the breaking of the main circuit. By this construction it will be seen that the bellshammer is completely under control of the main circuit, making a single stroke only when the proper change in the main circuit occurs, and it is actuated wholly, or substantially7 so, by the currentin the local circuit, although if the main circuit should be closed before the hammer had finished its forward stroke it might contribute to some extent to the force of the magnet that produced such stroke.

I claim- 1. The combination of an electro-magnet and armature therefor normally held in advance of ils retracted position with a switch operated by said armature at the ends of its movements toward and from the poles of the magnet, a local circuit through the said magnet controlled by the said switch, and a main circuit governing the operation of said magnet, whereby the armature is moved up to the poles of the magnet by the current of the local circuit after it is permitted to fall back by a momentary change in the main circuit, substantially as described.

2. The combi nat ion ofan electromagnet and its armature with a switch operated by the said armature at the end of its movement toward and from the poles of the magnet, an electric circuit through said magnet controlled by said switch, and a lock that cooperates with said armature, substantially as described.

3. The combination of an electroanagnet and its armature with a lock normally held, when said armature is attracted, in the position to permit the retractive movement of said arma- 5 tu re and engaged and moved from said normal position by thearmature in making its forward stroke, the said lock having a portionthat in the movement of the lock from the position in which it is placed by the armature making its forward stroke to its normal position affords an obstruction to the return movement of the armature, substantially as described.

4. The combination of an electro-magnetand armature therefor normally held in advance of 6 its retracted position with main and lo'eal eircuits through the coils of said magnet, each containing a source of electricity, and a eireuit-closer in said local circuit operated by the armature ofsaid magnet, the members of which 7 are separated when said armature is in its normal position and are engaged and placed in contact when said armature is in its retracted position, as and for the purpose described.

5. Thecombination, with thearmature-lever 7 provided with an engaging projection, of the lock for said armaturelever provided with a groove normally in the path of said projection when the armature makes its retractive movc mentand a spring closing the said groove and engaged by the said projection when the armature makes its forward movement, substalr tially as described.

ln testimony whereof I have signed my name to this specification inthe presence ol' two sub- 85 scribing witnesses.

MOSES (l. CRANE. XV itnesses:

Jos. lf. Lvumlonu, Jas. J. MA LoNnY. 

